The present invention relates to bumper systems for motor vehicles and, more particularly, to extendible bumper systems.
Motor vehicles typically have a bumper structure supported on a body of the motor vehicle by energy absorbers that convert into work a portion of the kinetic energy of a force on the bumper structure. Such bumper energy absorbers commonly include relatively movable structural elements attached to the body and the bumper structure and a resistance medium between the structural elements.
Extendible bumper systems include an actuator forming part of the bumper energy absorber for extending and retracting the bumper structure. Typically, these systems support the bumper structure close to the body of the motor vehicle during certain conditions, such as when the vehicle is being parked, and extend the bumper structure from the body during other conditions to increase the ability of the bumper energy absorbers to convert the kinetic energy of a force on the bumper structure into work.
In an exemplary embodiment, an extendible bumper system for a vehicle includes a controller system configured to: determine a distance of travel of a first end of a bumper structure using a signal from a position sensor in a first motor, determine a distance of travel of a second end of the bumper structure using a signal from a position sensor in a second motor, and independently adjusting at least one of rotational speed and torque generated by rotors in the first and second motors in response to the distances of travel.
In one embodiment, at least one of rotational speed and torque generated by the first and second rotors are independently adjusted in response to a difference in the distances of travel of the first and second ends of the bumper structure. In another embodiment, the rotational speeds of the first and second rotors are accelerated or decelerated during predetermined distances of travel.
In another aspect, a bumper energy absorber for supporting a bumper structure relative to a vehicle includes an outer tube is coupled to the vehicle, and an inner tube is disposed within the outer tube and coupled to the bumper structure. A lead screw is disposed within the inner tube, and a nut is threadably engaged to the lead screw. The inner tube is coupled to the nut. Fixed relative to the outer tube is a motor, which has its rotor coupled to the lead screw. Rotation of the lead screw by the rotor causes translation of the nut along the lead screw for driving at least a portion of the bumper structure between extended and retracted positions.